Field of the Invention
The present invention relates to a method of measuring a breakdown voltage of a semiconductor element and a method of manufacturing a semiconductor element, and particularly to a method of measuring a breakdown voltage of a semiconductor element with the use of an insulating liquid and a method of manufacturing a semiconductor element.
Description of the Background Art
In order to allow a semiconductor device to be high in breakdown voltage and low in loss and to be used in a high-temperature environment, silicon carbide has recently increasingly been adopted as a material forming a semiconductor device. Silicon carbide is a wide band gap semiconductor greater in band gap than silicon which has conventionally widely been used as a material forming a semiconductor device. Therefore, by adopting silicon carbide as a material forming a semiconductor device, a higher breakdown voltage of a semiconductor device can be achieved. Since a silicon carbide semiconductor device is high in breakdown voltage, a breakdown voltage of a silicon carbide semiconductor device may be measured with the use of an insulating liquid.
For example, Japanese Patent Laying-Open No. 2003-100819 discloses a method of examining a breakdown voltage of a device high in breakdown voltage. According to the method of examining a breakdown voltage, a breakdown voltage of the device high in breakdown voltage is measured while a wafer arranged on a stage is immersed in an insulating solution together with the stage. By immersing the wafer in the insulating solution, occurrence of atmospheric discharge can be suppressed even when a high voltage is applied to a device high in breakdown voltage.
International publication WO2010/021070 discloses a method of measuring a breakdown voltage of a metal oxide semiconductor field effect transistor (MOSFET). According to the method of measuring a breakdown voltage, initially, an insulating liquid is dropped onto a surface of a wafer so as to cover a source electrode pad and a gate electrode pad. Then, a breakdown voltage of the MOSFET is measured by bringing a probe in contact with the source electrode pad and the gate electrode pad in the insulating liquid. By using the insulating liquid, discharging from the probe can be suppressed even when a high voltage is applied to the source electrode pad.